1. Field of the Invention
The present invention relates to an evaporation method and an apparatus thereof, and more particularly to an evaporation method for improving the uniformity of a film deposited at the center of a substrate and an apparatus thereof.
2. Description of the Related Art
Generally, Physical Vapor Deposition (PVD) includes evaporation and sputtering. Both of them are performed by physical deposition. The evaporation deposition is performed by heating deposition material at the saturated vapor pressure thereof. It is usually performed in a vacuum evaporator, which includes an evaporation chamber and a vacuum system. The detailed description of prior art evaporation apparatus is described below.
FIG. 1 is a schematic showing a prior art evaporation apparatus. Referring to FIG. 1, an evaporation apparatus 100 is utilized to deposit metal or the other materials on a substrate 10, which can be, for example, a glass substrate. The evaporation apparatus 100 comprises a rotator 110, a heater 120, a source supplying device 130 and a shelter 140. The rotator 110 is disposed above the center of the substrate 10. The rotator 110 can rotate the substrate 10 by the center thereof. The heater 120 is disposed under the substrate 10. The heater 120 is usually made of refractory material. The heater 120 is connected to a power supply (not shown). When a current or voltage is supplied to the heater 120, the heater 120 generates heat because of its resistance. The source supplying device 130 is disposed over the heater 120. The source supplying device 130 supplies an evaporation source 122 to the heater 120 along a supplying direction S. The evaporation source 122 is provided by delivery of metal wires. The shelter 140 is disposed between the substrate 10 and the source supplying device 130. The shelter 140 has an opening 142. The opening 142 of the shelter 140 serves to define the evaporation region 124 on the substrate 10 formed by the evaporation source 122.
FIG. 2 is a top view showing a prior art evaporation apparatus. Referring to FIGS. 1 and 2, when the heater 120 heats the evaporation source 122 to the melting point thereof, the evaporation source 122 evaporates and deposits on the substrate 10. Theoretically, the evaporation source 122 provided by the source supplying device 130 is delivered to location A on the heater 120 and the edge of the evaporation region 124 aligns to the center of the substrate 10. A film is formed on the substrate 10 by rotating the substrate 10 for evaporation. However, the evaporation source 122 provided by the source supplying device 130 is not always delivered to location A; it could be delivered to location B or location C. The evaporation region 124 shifts because of different locations of the evaporation source 122.
As described above, if the evaporation source 122 provided by the source supplying device 130 is delivered to location B of the heater 120, the evaporations region 124 covers the center of the substrate 10. If the evaporation source 122 provided by the source supplying device 130 is delivered to location C of the heater 120, the evaporations region 124 does not cover the center of the substrate 10. Accordingly, different locations of the evaporation source 122 affect the uniformity of the film at the center of the substrate 10. Therefore, the uniformity of the film formed on the substrate becomes worse.